heart failure - use of medicines Flashcards
why do you use a high dose of diuretics in HF?
due to hypoperfusion, less of the diuretic is getting to the tubules and so you need to give a higher dose to have the save effect.
use of diuretics in HF
Preceded RCT’s BUT routinely used for relief of congestive symptoms and fluid retention
• Titrate up and down according to need, and initiation of other therapies
in HF - Which diuretic?
• Loop Diuretic Furosemide • Thiazides Bendrofluazide – Thiazide like Metolozone • Potassium Sparing Amilorde etc – Aldosterone antagonists Spironolactone
where do loop diuretics work
on the NA/K/CL symporter in the ascending loop of henle
where do thiazide diuretics work
on the Na/cl simperer in the DCT
where do K sparing diuretics work
on the ENaC in the collecting duct
common side effects from diuretics
- Hypokalaemia
- Hyponatraemia
- Volume depletion • Renal impairment • Gout
• Monitor urea, electrolytes and creatinine • Monitor volume status • Be vigilant for symptoms and signs of gout
• Renal impairment
– Rise in U&E’s, if small and asymptomatic acceptable, above 50% of baseline needs review
– Watch serum potassium, may need to reduce dose or stop
• Cough
– Only if troublesome consider switching to ARB’s
• Hypotension
– 1st dose, rarer now (captopril (old), not a problem with newer generations of drugs)
– Problematic in patients on other BP lowering meds
use of vasodilators in HF
• Organic nitrates – Veno-dilatory
• Hydralazine
– Arterial-dilatory
• Combination leads to improvement in cardiac output, reduction in pre and afterload
use of ACEI in HF
- Reduce mortality (20-25%) (CONSENSUS trial 1987 on enalapril found 31% better survival vs placebo)
- Effect more marked in patients with more severe LV dysfunction
- Benefit for all NYHA classes
- Reduces risk of hospitalisation and death (30- 35%)
- Patient should get symptomatic relief within a week or two
- PT can expect symptom improvement, reduced hospital admissions, and increase survival
there are lots of ACEI, which do you use?
if they are equivalent in action, use the cheapest and the ones with the greatest experience in practice.
fundamental choice in dosage decisions
start low and titrate up
Use of ARBs in HF?
- Patients who cannot tolerate ACEi
- Reduces mortality in patients vs placebo, head to head with ACEi, no survival benefit
- Few data on impact on qol, symptoms etc
- Examples all drugs ending in ‘sartan’ eg losartan, valsartan, candesartan
a HF PT on controlled well on meds presents with an exacerbation of the HF - first things to do?
1 - compliance?
2 - causes of exacerbation (arrhythmia, MI etc)
3 - escalate treatment
use of beta blockers in HF
• RCT/ meta analysis show that BB increase life expectancy vs placebo
• All NYHA classes
• Reduces hospitilisation
• All BB may not have same efficacy, evidence for bisoprolol, carvedilol and metoprolol (modified release), no evidence for atenolol
• Low dose titrate up, monitor heart rate, BP, clinical progression
- evidence is for metoprolol, bisoprolol and carvedilol.
side effects of beta blockers in HF
• Worsening signs and symptoms – may need to review dose
• Low heart rate
– review dose, check for heart block
• Hypotension
– may be asymptomatic
– If symptoms can alter other BP lowering meds
